Plugins on the list:

Automatically generate the Featured Image from the first image in post or any custom post type only if Featured Image is not set manually.

Categories: General

The Categories Images Plugin allow you to add image with category or taxonomy.

Categories: General

Makes local copies of all the linked images in a post, adding them as gallery attachments.

Categories: General

Automatically detect external images in the post content and import images to your site then adding to the media library and replace image urls.

Categories: General

Use an external image/video/audio as featured image of a post or WooCommerce product.

Categories: General

Import files from thrid-party services into Wordpress Media Library (Dropbox, Box, OneDrive, Google Drive, and any external file).

Categories: General

Allows you save an image from a remote URL to the WordPress media gallery, create local thumbnails and rename image.

Categories: General

Makes local copies of all the linked images and pdfs in a post, adding them as gallery attachments.

Categories: General

Upload files from an url to wordpress media library, either enter file urls in an onsite input box or click a bookmarklet.

Categories: General

Auto Save Remote Image

By Prebhdev Singh

This plugin automatically downloads the first remote image from a post and sets it as the featured image.

Categories: General

Using external images from anywhere to make thumbnail

Categories: General

External Media Upload

By Ravi Shakya

External Media Upload will grab media/files from external url link to your server and add…

Categories: General

Add external media to the media library

Categories: General

This plugin will download external images in your posts to your "wp-content/uploads" folder.

Categories: General

Add external images to the media library without importing, i.e. uploading them to your WordPress…

Categories: General